I've got a stomach ache.
You should drink something warm and rest. You shouldn't eat anything spicy or heavy for your stomach.
I want to have healthy teeth.
You should brush your teeth three times a day. You shouldn't eat after brushing your teeth.
I want to be fit.
You should exercise more. You shouldn't eat too much junk food.
I've got a terrible headache.
You should take a painkiller. You shouldn't listen to loud music.